At the start of a word, both English and German have one sibilant that can appear in some positions where no other consonant can appear. That sibilant is /s/ in English but /ʃ/ in German (pronounced roughly like <sh-> in English she).
The position where only English /s/ or German /ʃ/ can appear is at the beginning of a word starting with:
- a cluster of 3 consonants; or
- with some 2-consonant clusters.
Historical explanation
König and Gast explain this difference as follows: Proto-Germanic (the ancestor of both German and English) had only /s/ before other consonants in initial position.
Later on, High German—which includes modern standard German—replaced /s/ with /ʃ/. This innovation started before liquids such as /l/ (producing /ʃl/), then spread to nasals, then finally (except in some northern varieties of German) to the stops /p/ and /t/. This change has not spread to the remaining stop /k/.
A related change is that German does not have /s-/ as the sole consonant at the start of a word immediately before a vowel. In that position, German has only the voiced counterpart /z-/, even in words spelled with <s->. For example, sein (‘be’) is pronounced /zain/.
German does still distinguish /-s-/ from /-z-/ in the middle of words. For example, reisen (‘to travel’) is pronounced /raizən/ but reissen (‘to tear’) is pronounced /raisən/.
Some examples
The following table shows some examples of English words starting with /s-/ and some related German words starting with /ʃ-/.
Examples (2 consonant clusters)
| English | German |
| /stəʊn/ stone | [ʃtain/ stein (‘stone’) |
| /striːt/ street | [ʃtraːsə/ Straße (‘street’) |
| /spjuː/ spew | /ʃpaiən/ speien (‘to spew’) |
| /slːp/ sleep | /ʃlaːfən/ Schlafen (‘to sleep’) |
| /smaɪt/ smite | /ʃmaisən/ Schmeissen (‘to throw, chuck) |
| /snɔːr/ snore | /ʃnarçən/ schnarchen (to snore’) |
Exceptions
In a few instances, English has /ʃ/ instead of /s/:
- before /-r-/ in the sequence /ʃr-/, as in English shriek (see also German schreien, ‘to cry, shriek’). /-r-/ is the only consonant that can appear after /ʃ-/ at the start of an English word.
- before /-l-/ in loanwords starting with /ʃl-/, mainly from Yiddish or German
In a few instances, German has /s/ instead of/ʃ/:
- before /-k-/, when German allows only /s/ (eg Skrupel);
- rarely before /-l-/, mainly in names and loan words
- increasingly before /-t-/ in English loan words (eg steak, stewardess).
Sources
Understanding English-German Contrasts, by Ekkehard König and Volker Gast, 4th edition (2018)
The Phonology of German, Richard Wiese (1996). I haven’t seen the 2nd edition (2000)
The Phonology of English: a Prosodic Optimality-Theoretic Approach, Hammond (1999)
Germanic Syllable Structure, Marc van Oostendorp, in The Cambridge Handbook of Germanic Linguistics, edited by Michael T Putman and B Richard Page (2020)